Backup Pump

[Woody007]

I want to get a used pool pump to use as a backup, as well as for vacuuming the bottom for spring startup.
Currently I have a pakfab with 1.5hp single speed motor. I've found pakfab pumps, but the motors are either 1hp or 2hp, same rpm.
I'm guessing the lower hp would have to work harder and the 2hp would use more power than needed.
Is that correct or what should I be considering in this process?

 

[mas985]

A 2 HP pump will produce higher flow rates and higher pressure and use more energy on the same plumbing as a 1 HP pump. So in reality, a 2 HP is actually doing more work than a 1 HP pump. That is why the motor is larger and is designed to handle the extra work.

How do you plan on plumbing the second pump since it really needs its own separate suction line? Sharing suction lines between pumps is a really bad idea and can cause cavitation as well as other problems.

Why not just vacuum to waste using the existing pump instead of using a separate pump?

 

[Woody007]

A 2 HP pump will produce higher flow rates and higher pressure and use more energy on the same plumbing as a 1 HP pump. So in reality, a 2 HP is actually doing more work than a 1 HP pump. That is why the motor is larger and is designed to handle the extra work.

How do you plan on plumbing the second pump since it really needs its own separate suction line? Sharing suction lines between pumps is a really bad idea and can cause cavitation as well as other problems.

Why not just vacuum to waste using the existing pump instead of using a separate pump?

If the rpm is the same between my existing 1.5 and a different 2.0, how does it produce higher flow rate? Just asking, not arguing.
Regarding the plumbing, it would be a backup that would have to be installed when needed. That's why I've been searching for pakfab to match what I have.
Vac to waste works, but I really have trouble with the cap in the skimmer. It's a pain to keep it in place while getting a flow going even though I plug the other skimmer and don't use bottom drain.

 

[mas985]

The pump with the larger HP motor has a larger impeller so for a given RPM, generates more flow rate. If you compare the head curves, you will see the difference. The 2 HP pump will have a higher head curve than a 1 HP pump.

View attachment 536313

 

[Woody007]

The pump with the larger HP motor has a larger impeller so for a given RPM, generates more flow rate. If you compare the head curves, you will see the difference. The 2 HP pump will have a higher head curve than a 1 HP pump.

View attachment 536313

Thanks for the info. So for the same pump body the impeller would be different. Good to know as I search for a spare.
If I find pacfab with same motor hp as mine, then impeller would be same? Do these markings tell me what I need to know when looking?

 

[mas985]

Thanks for the info. So for the same pump body the impeller would be different. Good to know as I search for a spare.
If I find pacfab with same motor hp as mine, then impeller would be same? Do these markings tell me what I need to know when looking?

You need to match the motor THP (service factor * label HP) to the impeller. Post a picture of the motor label since that usually has both the label HP and the service factor.

However, any pool pump you get is going to have a motor attached so why does it matter what your current pump has vs the "spare"? Unless you plan on swapping parts.

But I am still not clear how you plan on using this "spare". How are you planning to plumb this pump into the existing plumbing?

 

[reggiehammond]

You should consider replacing single-speed with a variable speed pump (quieter and a lot of electrical savings).
Keep the single speed as a backup. But a small sump pump is all you need to keep water moving in case of a pump failure.

A robot would be a worthy investment if you're having trouble keeping the floor clean.

 

[Woody007]

You need to match the motor THP (service factor * label HP) to the impeller. Post a picture of the motor label since that usually has both the label HP and the service factor.

However, any pool pump you get is going to have a motor attached so why does it matter what your current pump has vs the "spare"? Unless you plan on swapping parts.

But I am still not clear how you plan on using this "spare". How are you planning to plumb this pump into the existing plumbing?

My goal is to have a spare pump (including motor) that I can install if I have a failure with current pump. Take off a couple of unions and wiring, slip in backup pump in its place. That's why I'm looking for pacfab since that's what I have now so the plumbing should be identical and an easy swap.
Make sense?

 

[mas985]

In 18 years of pool ownership, I have never needed a backup pump. But even if my pump failed, I don't see it as a big issue operating a pool without a pump for a short period of time. Mixing in the chemicals is the hardest part but if you have a robot, not an issue.

But for that application, it doesn't really matter if the replacement pump is the same HP as the original. All that matters is they use the same housing and if they are the same pump line, then the housing will be the same.

Note too that the impeller is attached to the motor so you can pull out the motor/impeller assembly and insert into the existing housing without having to remove the housing unless that is damaged.

In most cases, it is really only the motor that typically fails so having a standby for that, is all you really need.

 

[Newdude]

A submersible pump placed in the deep end with the hose running to the shallow end is a much cheaper solution if the pump is ever down for a spell.

 

[Woody007]

In 18 years of pool ownership, I have never needed a backup pump. But even if my pump failed, I don't see it as a big issue operating a pool without a pump for a short period of time. Mixing in the chemicals is the hardest part but if you have a robot, not an issue.

But for that application, it doesn't really matter if the replacement pump is the same HP as the original. All that matters is they use the same housing and if they are the same pump line, then the housing will be the same.

Note too that the impeller is attached to the motor so you can pull out the motor/impeller assembly and insert into the existing housing without having to remove the housing unless that is damaged.

In most cases, it is really only the motor that typically fails so having a standby for that, is all you really need.

Yeah, I'm probably overthinking it and have no real reason to think I would have a major failure requiring entire pump replacement. I half want a backup and half want a pump to vac the bottom in the spring.

 

[Newdude]

I get heavy spring debris next to a farm. At my last house I got it from being heavily wooded. I just vac my opening crud through the filter, give it several weeks for the pollen to fall and deep clean the filter once spring is done. The spring itself is far worse than the opening crud. My pressure says I don't need to clean it, but I do it for me for good measure. It more or less equals a mid season check because it's usually the first week in July by then. Then I'm good for the rest of the season without cleaning.